Selenium - Selenium automates browsers. That's it! What you do with that power is entirely up to you. Primarily, it is for automating web applications for testing purposes, but is certainly not limited to just that.
UserTesting.com - Usability testing has never been easier. Get videos of real people speaking their thoughts as they use websites, mobile apps, prototypes and more!
Sauce Labs - Test mobile or web apps instantly across 700+ browser/OS/device platform combinations - without infrastructure setup.
UserZoom - Test, measure, and monitor UX with our cost-effective all-in-one platform. UserZoom is a cloud-based solution for online usability testing.
Browsershots - Browsershots makes screenshots of your web design in different browsers.
Hotjar - The #1 Leader in Heatmaps, Recordings, Surveys & More. Sign up for a 15-day free trial and start learning from real user behavior today!